Catechins are reported to have physiological effects, such as a suppressing effect on the increase of cholesterol and an inhibitory effect on α-amylase activity (Patent Documents 1 and 2). For such effects to manifest, it is necessary for an adult to drink 4 to 5 cups of tea a day. Therefore, a technology enabling a beverage to contain a high concentration of catechins has been sought, so that catechins can be ingested conveniently in large amounts. Among such technologies is a method in which dissolved catechins are added to a beverage by making use of a concentrate of green tea extract (Patent Documents 3 to 5).
However, any commercially available concentrate of green tea extract could cause strong astringency and bitterness stemming from the components contained in the concentrate of green tea extract and is not good in the smooth flowing in the throat. From the standpoint of applicability for long-term drinking that is needed to actualize the physiological effects of catechins, a beverage that is reduced in the catechin astringency characteristic of a high catechin-containing beverage, has adequate sweetness and adequate sourness, and exhibits storage stability over a long period of time, has been sought. So far, a concentrated beverage composition for reconstitution has been developed that is easy to distribute before being packed in a beverage. This beverage, however, is not enough to reduce the bitterness of catechins (Patent Document 6).
In such a concentrated beverage composition for reconstitution, a preservative, specifically a hydroxycarboxylic acid, is generally used. Examples of the known methods that use a hydroxycarboxylic acid at the time of production of a beverage include a method in which ascorbic acid, a hydroxycarboxylic acid, is added to a tea extract or water in order to keep natural catechins in a good condition (Patent Documents 7 and 8), and a method in which catechins are extracted from green tea leaves using a ascorbic acid solution in order to obtain a green tea beverage which is smaller in the amount of leached tannin (Patent Document 9). However, there has so far been no report as to what influence could occur on a concentrate and its beverage obtained by the order of addition of a preservative such as ascorbic acid upon mixing the preservative in a beverage that contains non-polymer catechins.
[Patent Document 1] JP-A-60-156614
[Patent Document 2] JP-A-03-133928
[Patent Document 3] JP-A-2002-142677
[Patent Document 4] JP-A-08-109178
[Patent Document 5] JP-A-08-298930
[Patent Document 6] U.S. Pat. No. 6,413,570
[Patent Document 7] JP-A-2002-84973
[Patent Document 8] JP-A-2004-187613
[Patent Document 9] JP-A-02-13348